Methods for forming impurity free metal alloy films

ABSTRACT

Methods of depositing a metal film by exposing a substrate surface to a halide precursor and an organosilane reactant are described. The halide precursor comprises a compound of general formula (I): MQzRm, wherein M is a metal, Q is a halogen selected from Cl, Br, F or I, z is from 1 to 6, R is selected from alkyl, CO, and cyclopentadienyl, and m is from 0 to 6. The aluminum reactant comprises a compound of general formula (II) or general formula (III):wherein R1, R2, R3, R4, R5, R6, R7, R8, Ra, Rb, Rc, Rd, Re, and Rf are independently selected from hydrogen (H), substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ are independently selected from nitrogen (N) and carbon (C).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 16/991,430, filed on Aug. 12, 2020, the entire disclosure of whichis hereby incorporated by reference.

TECHNICAL FIELD

The invention generally relates to methods for atomic layer deposition(ALD) of metal films. In particular, embodiments of the invention aredirected to thermal-only based ALD deposition.

BACKGROUND

The transistor is a key component of most integrated circuits. Since thedrive current, and therefore speed, of a transistor is proportional tothe gate width of the transistor, faster transistors generally requirelarger gate width. Thus, there is a trade-off between transistor sizeand speed, and “fin” field-effect transistors (finFETs) have beendeveloped to address the conflicting goals of a transistor havingmaximum drive current and minimum size. FinFETs are characterized by afin-shaped channel region that greatly increases the size of thetransistor without significantly increasing the footprint of thetransistor, and are now being applied in many integrated circuits.However, finFETs have their own drawbacks.

As the feature sizes of transistor devices continue to shrink to achievegreater circuit density and higher performance, there is a need toimprove transistor device structure to improve electrostatic couplingand reduce negative effects such as parasitic capacitance and off-stateleakage. Examples of transistor device structures include a planarstructure, a fin field effect transistor (FinFET) structure, and ahorizontal gate all around (hGAA) structure. The hGAA device structureincludes several lattice matched channels suspended in a stackedconfiguration and connected by source/drain regions. It is believed thatthe hGAA structure provides good electrostatic control and can findbroad adoption in complementary metal oxide semiconductor (CMOS) wafermanufacturing.

Work function metal is of great interest in metal oxide semi-conductor(MOS) transistor applications. Metal films such as tantalum carbide(TaC), titanium carbide (TiC), titanium aluminum carbide (TiAlC), andtitanium aluminum (TiAl) have been evaluated as candidates for n-metals(work function metals) in MOS transistors.

Typically, the effective work function (WF) of metals and their alloysis governed by the effective electronegativity. More electropositivemetals demonstrate n-type metal oxide semiconductor (N-MOS) workfunction. The most widely used N-metal films include titanium (Ti),aluminum (Al), hafnium (Hf), and lanthanum (La). There are no viableoptions to deposit these pure metal films without plasma. Plasmaprocesses are typically undesirable for transistor manufacturing asplasma can cause detrimental effects on the previously deposited filmsand the resulting device. Therefore, there is a need in the art formethods to deposit these films with minimal electronegative residues.

SUMMARY

One or more embodiments of the disclosure are directed to a method ofdepositing a film. In one or more embodiments, the method comprises:exposing at least a portion of a substrate surface to a halide precursorcomprising a compound having the general formula (I) MQ_(z)R_(m) (I),wherein M is a metal, Q is a halogen selected from Cl, Br, F or I, z isfrom 1 to 6, R is selected from alkyl, CO, cyclopentadienyl, amidinate,diazadiene, or amidate, and m is from 0 to 6; and exposing at least aportion of the substrate surface to an organosilane reactant comprisinga compound of general formula (II) or general formula (III)

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C), to deposit ametal film on the substrate surface, the metal film substantially freeof carbon.

Additional embodiments of the disclosure are directed to an electronicdevice. In one or more embodiment, a gate stack comprises: a high-Kdielectric layer on a substrate; a first titanium nitride layer on thehigh-K dielectric layer; a work-function layer on the first titaniumnitride layer; and a second titanium nitride layer on the work-functionlayer, wherein the work-function layer comprises a metal filmsubstantially free of carbon.

Further embodiments of the disclosure are directed to a non-transitorycomputer readable medium including instructions, that, when executed bya controller of a processing chamber, causes the processing chamber toperform operations of: flow a halide precursor into a processing volumeof the processing chamber having a substrate, the halide precursorhaving general Formula (I) MQ_(z)R_(m) (I), wherein M is a metal, Q is ahalogen selected from Cl, Br, F or I, z is from 1 to 6, R is selectedfrom alkyl, CO, cyclopentadienyl, amidinate, diazadiene, or amidate, andm is from 0 to 6, purge the processing chamber of the halide precursor;expose the substrate to a organosilane precursor of general Formula (II)or general Formula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C); and purge theprocessing chamber of the organosilane precursor.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 illustrates a process flow diagram of a method according toembodiments described herein; and

FIG. 2 illustrates a cross-section view of a metal oxide stack accordingto embodiments described herein.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

As used in this specification and the appended claims, the term“substrate” refers to a surface, or portion of a surface, upon which aprocess acts. It will also be understood by those skilled in the artthat reference to a substrate can also refer to only a portion of thesubstrate, unless the context clearly indicates otherwise. Additionally,reference to depositing on a substrate can mean both a bare substrateand a substrate with one or more films or features deposited or formedthereon

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/orbake the substrate surface. In addition to film processing directly onthe surface of the substrate itself, in the present disclosure, any ofthe film processing steps disclosed may also be performed on anunderlayer formed on the substrate as disclosed in more detail below,and the term “substrate surface” is intended to include such underlayeras the context indicates. Thus for example, where a film/layer orpartial film/layer has been deposited onto a substrate surface, theexposed surface of the newly deposited film/layer becomes the substratesurface.

As used in this specification and the appended claims, the terms“reactive gas”, “precursor”, “reactant”, and the like, are usedinterchangeably to mean a gas that includes a species which is reactivein an atomic layer deposition process. For example, a first “reactivegas” may simply adsorb onto the surface of a substrate and be availablefor further chemical reaction with a second reactive gas.

In one or more embodiments, methods for thermal-only based atomic layerdeposition (ALD) deposition of metal films particularly one or more oftitanium and/or aluminum, are described. Some embodiments advantageouslyprovide methods for forming stable compositions with greater than 95%step coverage. Some embodiments of the method advantageously providework function metals for gate-all-around (GAA) architectures.

Typically, alloys of two electropositive elements are deposited using ahalide metal for the first element and a metal-organic based precursorfor the second element. An oxidation-reduction reaction between theprecursors deposits an alloy film. However, the oxidation-reductionreaction forms carbon residues, which can reduce the ability of the filmto exhibit the best effective work function. One or more embodimentsadvantageously provides an alloy film that is substantially free ofimpurities, e.g. carbon, with a controlled composition.

Titanium (Ti) and aluminum (Al) are both electropositive metals and arevery difficult to reduce. Some embodiments of the disclosure providethermal vapor phase deposition of pure metal films. Some embodimentsadvantageously permit compositional control of the alloy films bycontrolling the reactants.

In one or more embodiments, thermal atomic layer deposition (ALD)methods are provided that involve the reduction of a metal halideprecursor with an organosilane reducing agent.

“Atomic layer deposition” or “cyclical deposition” as used herein refersto the sequential exposure of two or more reactive compounds to deposita layer of material on a substrate surface. As used in thisspecification and the appended claims, the terms “reactive compound”,“reactive gas”, “reactive species”, “precursor”, “process gas” and thelike are used interchangeably to mean a substance with a species capableof reacting with the substrate surface or material on the substratesurface in a surface reaction (e.g., chemisorption, oxidation,reduction). The substrate, or portion of the substrate, is exposedseparately to the two or more reactive compounds which are introducedinto a reaction zone of a processing chamber.

In a time-domain ALD process, exposure to each reactive compound isseparated by a time delay to allow each compound to adhere and/or reacton the substrate surface and then be purged from the processing chamber.In a spatial ALD process, different portions of the substrate surface,or material on the substrate surface, are exposed simultaneously to thetwo or more reactive compounds so that any given point on the substrateis substantially not exposed to more than one reactive compoundsimultaneously. As used in this specification and the appended claims,the term “substantially” used in this respect means, as will beunderstood by those skilled in the art, that there is the possibilitythat a small portion of the substrate may be exposed to multiplereactive gases simultaneously due to diffusion, and that thesimultaneous exposure is unintended.

In time-domain ALD embodiments, exposure to each of the process gasesare separated by a time delay/pause to allow the components of theprocess gases to adhere and/or react on the substrate surface.Alternatively, or in combination, in some embodiments, a purge may beperformed before and/or after the exposure of the substrate to theprocess gases, wherein an inert gas is used to perform the purge. Forexample, a first process gas may be provided to the process chamberfollowed by a purge with an inert gas. Next, a second process gas may beprovided to the process chamber followed by a purge with an inert gas.In some embodiments, the inert gas may be continuously provided to theprocess chamber and the first process gas may be dosed or pulsed intothe process chamber followed by a dose or pulse of the second processgas into the process chamber. In such embodiments, a delay or pause mayoccur between the dose of the first process gas and the second processgas, allowing the continuous flow of inert gas to purge the processchamber between doses of the process gases.

In one aspect of a time-domain ALD process, a first reactive gas (i.e.,a first precursor or compound A) is pulsed into the reaction zonefollowed by a first time delay. Next, a second precursor or compound Bis pulsed into the reaction zone followed by a second delay. During eachtime delay, a purge gas, such as argon, is introduced into theprocessing chamber to purge the reaction zone or otherwise remove anyresidual reactive compound or reaction by-products from the reactionzone. Alternatively, the purge gas may flow continuously throughout thedeposition process so that only the purge gas flows during the timedelay between pulses of reactive compounds. The reactive compounds arealternatively pulsed until a desired film or film thickness is formed onthe substrate surface. In either scenario, the ALD process of pulsingcompound A, purge gas, compound B and purge gas is a cycle. A cycle canstart with either compound A or compound B and continue the respectiveorder of the cycle until achieving a film with the predeterminedthickness.

In one or more embodiments, the purge gas is selected from one or moreof argon (Ar), nitrogen (N₂), or helium (He). In one or moreembodiments, the same purge gas is used to purge the precursor and thereductant. In other embodiments, a different purge gas is used to purgethe processing chamber of the precursor than the purge gas used to purgethe processing chamber of the oxidant.

In an embodiment of a spatial ALD process, a first reactive gas andsecond reactive gas are delivered simultaneously to the reaction zonebut are separated by an inert gas curtain and/or a vacuum curtain. Thesubstrate is moved relative to the gas delivery apparatus so that anygiven point on the substrate is exposed to the first reactive gas andthe second reactive gas.

In spatial ALD embodiments, exposure to each of the process gases occurssimultaneously to different parts of the substrate so that one part ofthe substrate is exposed to the first reactive gas while a differentpart of the substrate is exposed to the second reactive gas (if only tworeactive gases are used). The substrate is moved relative to the gasdelivery system so that each point on the substrate is sequentiallyexposed to both the first and second reactive gases. In any embodimentof a time-domain ALD or spatial ALD process, the sequence may berepeated until a predetermined layer thickness is formed on thesubstrate surface.

A “pulse” or “dose” as used herein is intended to refer to a quantity ofa source gas that is intermittently or non-continuously introduced intothe process chamber. The quantity of a particular compound within eachpulse may vary over time, depending on the duration of the pulse. Aparticular process gas may include a single compound or amixture/combination of two or more compounds, for example, the processgases described below.

The durations for each pulse/dose are variable and may be adjusted toaccommodate, for example, the volume capacity of the processing chamberas well as the capabilities of a vacuum system coupled thereto.Additionally, the dose time of a process gas may vary according to theflow rate of the process gas, the temperature of the process gas, thetype of control valve, the type of process chamber employed, as well asthe ability of the components of the process gas to adsorb onto thesubstrate surface. Dose times may also vary based upon the type of layerbeing formed and the geometry of the device being formed. A dose timeshould be long enough to provide a volume of compound sufficient toadsorb/chemisorb onto substantially the entire surface of the substrateand form a layer of a process gas component thereon.

In one or more embodiments, the films described herein may be formed byatomic layer deposition (ALD) processes using a metal halide precursorand an organosilane reducing agent. The atomic layer deposition processof one or more embodiments is a thermal process and does not involve theuse of a plasma.

As used herein “metal film” refers to a film that comprises a metal. Inone or more embodiments, the metal film is substantially freeimpurities. In one or more embodiments, the metal film is substantiallyfree of carbon (C) despite the substrate being exposed to acarbon-containing organosilane precursor/reductant. As used herein, theterm “substantially free” means that there is less than about 5%,including less than about 4%, less than about 3%, less than about 2%,less than about 1%, and less than about 0.5% of carbon, on an atomicbasis, in the metal film.

In one or more embodiments, the metal film contains greater than about90% total metal content on an atomic basis, including greater than about95% total metal, greater than about 96% total metal, greater than about97% total metal, greater than about 98% total metal, or greater thanabout 99% total metal. As used herein, the term “total metal content”refers to the percentage of metal, on an atomic basis, present in themetal film. In one or more embodiments, the metal may come from thehalide precursor.

In one or more embodiments, the metal halide precursor comprises acompound having the general Formula (I): MQ_(z)R_(m) (I), wherein M is ametal, Q is a halogen selected from Cl, Br, F or I, z is from 1 to 6, Ris selected from alkyl, CO, cyclopentadienyl, amidinate, diazadiene, oramidate, and m is from 0 to 6.

In one or more embodiments, the metal, M, is selected from one or moremetal from group III, group IV, group V, group VI, or group VII of theperiodic table, or Sn or Si. In other embodiments, the metal, M, isselected from one or more of scandium (Sc), yttrium (Y), lanthanum (La),actinium (Ac), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium(V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo),tungsten (W), manganese (Mn), rhenium (Re), technetium (Tc), iron (Fe),ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir),nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag),gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), tin (Sn), or (silicon)Si. In one or more embodiments, the metal M is selected from one or moreof Ti, Ta, Zr, La, Hf, Ce, Zn, Cr, Sn, W, or V. In one or more specificembodiments, the metal M is selected from one or more of titanium (Ti)and aluminum (Al).

In one or more embodiments, Q is a halogen selected from Cl, Br, F, orI. In one or more embodiments, z is from 1 to 6, including 1, 2, 3, 4,5, or 6. In other embodiments, Q is selected from Cl or Br. In aspecific embodiment, Q is Cl. In another specific embodiment, Q is Br.

Unless otherwise indicated, as used herein, “alkyl,” or “alk” includesboth straight and branched chain hydrocarbons, containing 1 to 20carbons, in the normal chain, such as methyl, ethyl, propyl, isopropyl,butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl,4,4-dimethylpentyl, octyl, 2,2,4-trimethyl-pentyl, nonyl, decyl,undecyl, dodecyl, the various branched chain isomers thereof, and thelike. Such groups may optionally include up to 1 to 4 substituents. Inone or more embodiments, R is selected from alkyl, CO, cyclopentadienyl,amidinate, diazadiene, or amidate. In one or more embodiments, R is C₁₋₆alkyl. In one or more embodiments, m is from 0 to 6, including 0, 1, 2,3, 4, 5, or 6.

In one or more embodiments, the organosilane reducing agent has astructure of Formula II or Formula III:

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C).

The term “lower alkyl,” “alkyl,” or “alk” as used herein alone or aspart of another group includes both straight and branched chainhydrocarbons, containing 1 to 20 carbons, in the normal chain, such asmethyl, ethyl, propyl, isopropyl, butyl, t-butyl, isobutyl, pentyl,hexyl, isohexyl, heptyl, 4,4-dimethylpentyl, octyl,2,2,4-trimethyl-pentyl, nonyl, decyl, undecyl, dodecyl, the variousbranched chain isomers thereof, and the like. Such groups may optionallyinclude up to 1 to 4 substituents. The alkyl may be substituted orunsubstituted. In specific embodiments, at least one of R^(a), R^(b),R^(c), R^(d), R^(e), and R^(f) comprise methyl. In some embodiments,each of R^(a), R^(b), R^(c), R^(d), R^(e), and R^(f) comprise methyl.

In one or more embodiments, the organosilane reducing agents areselected from bis(trimethylsilyl)cyclohexadiene,bis(trimethylsilyl)diaza-cyclohexadiene,bis(trimethylsilyl)-aza-cyclohexadiene,bis(trimethylsilyl)-dihydro-bipyridine,3,6-bis(trimethylsilyl)-1,4-cyclohexadiene,1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene, and1,4-bis-(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene.

With reference to FIG. 1, one or more embodiments of the disclosure aredirected to method 10 of depositing a thin film. The method illustratedin FIG. 1 is representative of a thermal atomic layer deposition (ALD)process in which the substrate or substrate surface is exposedsequentially to the reactive gases in a manner that prevents orminimizes gas phase reactions of the reactive gases.

In some embodiments, the method 10 includes an optional pre-treatmentoperation 20. The pre-treatment can be any suitable pre-treatment knownto the skilled artisan. Suitable pre-treatments include, but are notlimited to, pre-heating, cleaning, soaking, native oxide removal, ordeposition of an adhesion layer (e.g. titanium nitride (TiN)). In one ormore embodiments, an adhesion layer, such as titanium nitride, isdeposited at pre-treatment operation 20.

With reference to FIG. 1, the method 10 comprises a deposition cycle 70.At deposition operation 30, a process is performed to deposit ametal-containing film on the substrate (or substrate surface). Atoperation 30, the substrate (or substrate surface) is exposed to ahalide precursor comprising a compound having the general Formula (I):MQ_(z)R_(m) (I), wherein M is a metal, Q is a halogen selected from Cl,Br, F or I, z is from 1 to 6, R is selected from alkyl, CO,cyclopentadienyl, amidinate, diazadiene, or amidate, and m is from 0 to6. In one or more specific embodiments, the halide precursor comprisestitanium tetrachloride (TiCl₄) to form a titanium species on thesubstrate surface. In other embodiments, the halide precursor comprisesaluminum chloride (AlCl₃) to form an aluminum species on the substratesurface.

In one or more embodiments, the halide precursor-containing process gasmay be provided in one or more pulses or continuously. The flow rate ofthe halide precursor-containing process gas can be any suitable flowrate including, but not limited to, flow rates is in the range of about1 to about 5000 sccm, or in the range of about 2 to about 4000 sccm, orin the range of about 3 to about 3000 sccm or in the range of about 5 toabout 2000 sccm. The halide precursor of Formula I can be provided atany suitable pressure including, but not limited to, a pressure in therange of about 5 mTorr to about 40 Torr, or in the range of about 100mTorr to about 40 Torr, or in the range of about 5 Torr to about 40Torr, or in the range of about 50 mTorr to about 2000 mTorr, or in therange of about 100 mTorr to about 1000 mTorr, or in the range of about200 mTorr to about 500 mTorr.

In one or more embodiments, the period of time that the substrate isexposed to the halide precursor-containing process gas may be anysuitable amount of time necessary to allow the precursor to form anadequate nucleation layer atop the conductive substrate surfaces. Forexample, the process gas may be flowed into the process chamber for aperiod of about 0.1 seconds to about 90 seconds. In some time-domain ALDprocesses, the substrate surface is exposed to the halideprecursor-containing process gas for a time in the range of from about0.1 sec to about 90 sec, or in the range of from about 0.5 sec to about60 sec, or in the range of from about 1 sec to about 30 sec, or in therange of from about 2 sec to about 25 sec, or in the range of from about3 sec to about 20 sec, or in the range of from about 4 sec to about 15sec, or in the range of from about 5 sec to about 10 sec.

In some embodiments, an inert carrier gas may additionally be providedto the process chamber at the same time as the halideprecursor-containing process gas. The carrier gas may be mixed with thehalide precursor-containing process gas (e.g., as a diluent gas) orseparately and can be pulsed or of a constant flow. In some embodiments,the carrier gas is flowed into the processing chamber at a constant flowin the range of from about 1 to about 10000 sccm. The carrier gas may beany inert gas, for example, such as argon (Ar), nitrogen (N), helium(He), neon (Ne), combinations thereof, or the like. In one or morespecific embodiments, the halide precursor-containing process gas ismixed with argon prior to flowing into the process chamber.

In one or more embodiments, the temperature of the substrate duringdeposition can be controlled, for example, by setting the temperature ofthe substrate support. In some embodiments the substrate is held at atemperature in a range of from about 100° C. to about 500° C., includinga temperature of about 100° C., about 150° C., about 200° C., about250°, about 300° C., about 350° C., about 400° C., about 450° C., andabout 500° C.

In one or more embodiments, at operation 40, the processing chamber isthen purged of the halide precursor. Purging can be accomplished withany suitable gas that is not reactive with the substrate, film on thesubstrate, and/or processing chamber walls. Suitable purge gasesinclude, but are not limited to, nitrogen (N₂), helium (He), and argon(Ar). The purge gas may be used to purge the processing chamber of thehalide precursor, and/or the organosilane reactant. In some embodiments,the same purge gas is used for each purging operation. In otherembodiments, a different purge gas is used for the various purgingoperations.

In one or more embodiments, at operation 50, at least a portion of thesubstrate surface is exposed to an organosilane reactant to deposit ametal film. The organosilane reactant comprising a compound of generalformula (II) or general formula (III)

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C).

In one or more specific embodiments, the organosilane precursor reactswith the metal species on the substrate surface to form a metal film.For example, in embodiments where the halide precursor comprisestitanium tetrachloride (TiCl₄), the organosilane precursor reduces thetitanium species and forms a titanium film.

In one or more embodiments, at operation 60, the processing chamber isthen purged of the organosilane reactant. In one or more embodiments,the metal film is deposited on the substrate surface. In one or moreembodiments, the metal film is substantially free of carbon.

At decision 80, the thickness of the deposited film, or number of cyclesof halide precursor and organosilane precursor is considered. If thedeposited film has reached a predetermined thickness or a predeterminednumber of process cycles have been performed, the method 10 moves to apost-processing operation 90. If the thickness of the deposited film orthe number of process cycles has not reached the predeterminedthreshold, the method 10 returns to deposition operation 70 to exposethe substrate surface to the halide precursor again in operation 30, andcontinuing.

In one or more embodiments, the deposition cycle 70 is repeated. Atoperation 30, the halide precursor of Formula I comprises a differentprecursor that in the first deposition cycle. For example, in one ormore embodiments, the halide precursor comprises aluminum chloride(AlCl₃) to form an aluminum species, which is then subsequently reducedby the organosilane precursor. In some embodiments, the precursors maynot change every other cycle. In some embodiments, for example, theremay be five cycles with one precursor and then three cycles with theother precursor.

The optional post-processing operation 90 can be, for example, a processto modify film properties (e.g., annealing or densification) or afurther film deposition process (e.g., additional ALD or CVD processes)to grow additional films. In some embodiments, the post-processingoperation 90 can be a process that modifies a property of the depositedfilm. In some embodiments, the post-processing operation 90 comprisesannealing the as-deposited film. In some embodiments, annealing is doneat temperatures in the range of about 300° C., 400° C., 500° C., 600°C., 700° C., 800° C., 900° C. or 1000° C. The annealing environment ofsome embodiments comprises one or more of an inert gas (e.g., molecularnitrogen (N₂), argon (Ar)) or a reducing gas (e.g., molecular hydrogen(H₂) or ammonia (NH₃)) or an oxidant, such as, but not limited to,oxygen (O₂), ozone (O₃), or peroxides. Annealing can be performed forany suitable length of time. In some embodiments, the film is annealedfor a predetermined time in the range of about 15 seconds to about 90minutes, or in the range of about 1 minute to about 60 minutes. In someembodiments, annealing the as-deposited film increases the density,decreases the resistivity and/or increases the purity of the film.

In one or more embodiments, the method 10 can be performed at anysuitable temperature depending on, for example, the halide precursor,organosilane reducing agent, or thermal budget of the device. In someembodiments, exposures to the halide precursor (operation 30) and theorganosilane reducing agent (operation 50) occur at the sametemperature. In some embodiments, the substrate is maintained at atemperature in a range of about 200° C. to about 500° C., or in therange of about 350° C. to about 500° C.

In one or more embodiments, the metal film, titanium aluminum (TiAl)film has a carbon content of less than or equal to about 5% on an atomicbasis.

In one or more embodiments, the metal film, which comprises less than orequal to about 5% carbon on an atomic basis, may be subjected to furtherprocessing to form a metal carbide film. In such embodiments, the metalportion of the carbide film, e.g. titanium aluminum (TiAl), containsless than about 5% carbon impurity.

In one or more embodiments, the method is used to deposit pure thermaltitanium (Ti) metal and (aluminum) Al metal which can be processedfurther to yield a TiAl film. The deposited film may have certain degreeof C incorporation and can form TiAlC.

One or more embodiments of the disclosure are directed to a metal oxidestack that is part of a gate stack in a metal oxide semiconductor (MOS).Referring to FIG. 2, the metal oxide stack 100 comprises a high-κdielectric layer 104 on a substrate 102, and a titanium nitride layer106 on the high-κ dielectric layer 104. The embodiment illustrated inFIG. 2 has a separate high-K dielectric layer 104 on a substrate 102.However, the skilled artisan will recognize that the high-κ dielectriclayer 104 can be the substrate 102 or a portion of the substrate 102.For example, the high-κ dielectric 104 can be formed on the substrate102 to form the metal oxide stack 100.

In one or more embodiments, the metal oxide stack 100 is formed onsubstrate 102 which can be any suitable material or shape. In theembodiment illustrated, the substrate 102 is a flat surface and themetal oxide stack 100 is represented by rectangular boxes placed on topof one another. However, those skilled in the art will understand thatthe substrate 102 can have one or more features (i.e., trenches or vias)and that the metal oxide stack 100 can be formed to conform to the shapeof the substrate 102 surface.

In one or more embodiments, a work function layer 108 is formed on thetitanium nitride layer 106. In one or more embodiments, the workfunction layer 108 comprises a metal film that is substantially free ofcarbon, having less than about 5% carbon on an atomic basis. The metalfilm is prepared by the methods of one or more embodiments. The metalfilm can be formed by exposing at least a portion of the substrate 102to a halide precursor comprising a compound having the general Formula(I): MQ_(z)R_(m) (I), wherein M is a metal, Q is a halogen selected fromCl, Br, F or I, z is from 1 to 6, R is selected from alkyl, CO,cyclopentadienyl, amidinate, diazadiene, or amidate, and m is from 0 to6; and exposing at least a portion of the substrate 102 to anorganosilane reducing agent comprising a compound of general formula(II) or general formula (III)

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C), to deposit ametal film as a work function layer 108 on the substrate 102, the metalfilm substantially free of carbon.

In some embodiments, exposing the substrate surface to the halideprecursor and the organosilane reactant occurs sequentially. Forexample, an ALD type process so that the substrate surface (or portionthereof) is exposed to the halide precursor and the organosilanereactant sequentially or substantially sequentially. In someembodiments, exposing the substrate surface to the halide precursor andthe organosilane reactant occurs simultaneously. For example, a chemicalvapor deposition (CVD) type process in which both the halide precursorand the organosilane reactant are flowed into the processing chamber atthe same time, allowing gas phase reactions of the precursor and thereactant.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or the substrate can be moved from the first chamberto one or more transfer chambers, and then moved to the separateprocessing chamber. Accordingly, the processing apparatus may comprisemultiple chambers in communication with a transfer station. An apparatusof this sort may be referred to as a “cluster tool” or “clusteredsystem”, and the like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, degassing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific portions of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,degas, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants after forming the layer on thesurface of the substrate. According to one or more embodiments, a purgegas is injected at the exit of the deposition chamber to preventreactants from moving from the deposition chamber to the transferchamber and/or additional processing chamber. Thus, the flow of inertgas forms a curtain at the exit of the chamber.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support (e.g.,susceptor) and flowing heated or cooled gases to the substrate surface.In some embodiments, the substrate support includes a heater/coolerwhich can be controlled to change the substrate temperatureconductively. In one or more embodiments, the gases (either reactivegases or inert gases) being employed are heated or cooled to locallychange the substrate temperature. In some embodiments, a heater/cooleris positioned within the chamber adjacent the substrate surface toconvectively change the substrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposure todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the materials and methods discussed herein(especially in the context of the following claims) are to be construedto cover both the singular and the plural, unless otherwise indicatedherein or clearly contradicted by context. Recitation of ranges ofvalues herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate the materials and methods and does not pose a limitation onthe scope unless otherwise claimed. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the disclosed materials and methods.

Reference throughout this specification to “one embodiment,” “someembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in some embodiments,” “in one embodiment” or “in anembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A non-transitory computer readable mediumincluding instructions, that, when executed by a controller of aprocessing chamber, causes the processing chamber to perform operationsof: flow a first halide precursor into a processing volume of theprocessing chamber having a substrate, the first halide precursor havinggeneral Formula (I)MQ_(z)R_(m)  (I), wherein M is a metal comprising titanium (Ti), Q is ahalogen selected from Cl, Br, F or I, z is from 1 to 6, R is selectedfrom alkyl, CO, cyclopentadienyl, amidinate, diazadiene, or amidate, andm is from 0 to 6, purge the processing chamber of the first halideprecursor; expose the substrate to an organosilane precursor of generalFormula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R^(a), R^(b), R^(c), R^(d),R^(e), and R^(f) are independently selected from hydrogen (H),substituted alkyl or unsubstituted alkyl; and X, Y, X′, and Y′ areindependently selected from nitrogen (N) and carbon (C): purge theprocessing chamber of the organosilane precursor; flow a second halideprecursor into a processing volume of the processing chamber having asubstrate, the second halide precursor; purge the processing chamber ofthe second halide precursor aluminum chloride (AlCl₃); expose thesubstrate to the organosilane precursor of general Formula (III); andpurge the processing chamber of the organosilane precursor.
 2. Thenon-transitory computer readable medium of claim 1, wherein Q is Cl orBr.
 3. The non-transitory computer readable medium of claim 1, wherein Qis Cl.
 4. The non-transitory computer readable medium of claim 1,wherein at least one of R^(a), R^(b), R^(c), R^(d), R^(c), and R^(f)comprises methyl.
 5. The non-transitory computer readable medium ofclaim 1, wherein exposing the substrate surface to the first halideprecursor and the organosilane reactant occurs sequentially.
 6. Thenon-transitory computer readable medium of claim 1, wherein exposing thesubstrate surface to the first halide precursor and the organosilanereactant occurs simultaneously.
 7. The non-transitory computer readablemedium of claim 1, wherein the substrate is in a processing chamber. 8.The non-transitory computer readable medium of claim 7, furthercomprising purging the processing chamber of each of the first halideprecursor and the second halide precursor prior to exposing thesubstrate to the organosilane reactant.
 9. The non-transitory computerreadable medium of claim 8, further comprising purging the processingchamber of the organosilane reactant.
 10. The non-transitory computerreadable medium of claim 1, wherein m is from 1 to
 6. 11. A gate stackcomprising: a high-κ dielectric layer on a substrate; a first titaniumnitride layer on the high-κ dielectric layer; a work-function layer onthe first titanium nitride layer; and a second titanium nitride layer onthe work-function layer, wherein the work-function layer comprises ametal film having more than one metal M, the metal film substantiallyfree of carbon.
 12. The gate stack of claim 11, wherein the metal filmcomprises one or more of titanium (Ti) and aluminum (Al).
 13. The gatestack of claim 11, wherein the work function layer comprises titaniumaluminum carbide (TiAlC).